Hallo Namenloser,
das ist eine gute Frage - aber aus meiner Sicht ein grundlegend falscher Ansatz.
Wie gesagt: Aus meiner Sicht. Notes ist von seinem grundlegendem Aufbau, seiner "Philosophie" ein verteiltes System. Man sollte daher Notes-Applikationen immer so aufbauen, dass Replizierkonflikte erst gar nicht entstehen können. Dafür gibt es zahlreiche Strategien. Wenn man natürlich versucht, ein relationales System nachzubilden, hat man entweder einen grösseren Aufwand, oder man hat das falsche System ausgewählt.
Unter dieser Prämisse muss meine Antwort unter der Prämisse stehen: "AFAIK". Ich meide aus den oben genannten Gründen Document Locking wie der Teufel das Weihwasser
Was meine Quellen sagen: (Hard) Locking funktioniert über "alle" Repliken hinweg. Was natürlich eine schlichte Falschaussage ist - lokale Repliken sollen ja nicht unüblich sein
Das allein führt die Sache ggf. schon ad absurdum.
Meine Erfahrung: Selbst über Server hinweg kommt es zu Problemen (es wird nicht unlocked, es kann nicht gelocked werden - da reichen trivialste Gründe).
Mein Fazit: Man sollte die Architektur der DB anpassen, um Replizierkonflikte zu vermeiden, oder man sollte einfache Werkzeuge schaffen, um gelegentliche Replizierkonflikte auch durch bestimmte User selbst auflösen zu können.
Was Dokus angeht - wieder AFAIK: Das ausführlichste steht unter "Dokumente sperren" in der UserHelp.NSF. In der KBase sieht es auch dünne aus:
How Does Notes Domino 6 Document Locking Feature Work?
Product:
Lotus Domino > Lotus Domino Designer > Version 6.0
Platform(s):
AIX, i5/OS, Linux, Solaris, Windows
Doc Number:
7003259
Published 10.10.2002
Product documentation
Abstract
This paper is intended to give a brief overview of document locking, which is a new feature beginning with Notes Domino 6 (ND6). Document locking is a way to dramatically reduce replication/save conflicts, and to otherwise ensure that when one user is editing a document, no one else will try to do so.
Content
This paper is intended to give a brief overview of document locking, which is a new feature beginning with Notes Domino 6 (ND6).
Document locking is a way to dramatically reduce replication/save conflicts, and to otherwise ensure that when one user is editing a document, no one else will try to do so. If the document is in a database replicated amongst Domino 6 servers that communicate easily with one another, then the feature works very smoothly. If some of the servers are extremely remote, or are in different domains and do not communicate directly with each other, or the system is a mix of R5 and Domino 6, then various problems will ensue.
How to enable document locking
- Enable the feature called "Allow document locking" on the first tab of the Database Properties dialog box
- The database needs to be ODS 43 (ND6)
- You will need to have an administrative server selected in the ACL
- You do not need to compact the database
What happens once document locking is enabled
Once enabled, you will find that every time you edit a document, the status bar indicates, "Document successfully locked." Likewise, when saving/closing a document, "Document successfully unlocked" is written to the status bar. This requires no extra steps for your users. Behind the scenes, whenever the document is put in/out of edit mode, two fields are written to: $Writers and $WritersDate. The first field is a read/write access names field, the same as an AuthorNames field. The second field is a time/date stamp. These fields are used to let the system know that the document is locked. When unlocked, these fields are blanked out.
Note that you can alternatively lock/unlock a document via the Actions menu (or right-click and choose Lock/Unlock from the pop-up menu). If you lock a document this way, it remains locked until you unlock it. If you lock a document implicitly by simply editing the document, it unlocks automatically when you come out of edit mode.
If the database has no replica copies, then using this feature is trivial. But let us assume that there are replica copies on multiple servers, etiher multiple single servers or in a clustered environment. In that case, when you try to edit a document, the server makes a call to the administrative server to make sure that this document is not locked. If it is locked, you are given an appropriate error message. If it is not locked, then you are given the lock. For this reason, it is critical to the smooth functioning of this feature that the servers can all communicate with the administrative server easily. If they cannot, or if that communication is slow, then your users will experience a host of problems, from incomplete error messages to an inability to edit/save the document.
Note that the feature can handle local and dial-up access. It gives the user a message to the effect that it will try to synchronize the edits when connected, and will generate a rep/save conflict only if necessary. The user will get an email message with the results of this attempt.
What happens in a mixed environment
- R5 client trying to edit an unlocked document. This is not a problem.
- R5 client trying to edit a locked document. Client generates an error message on save, cannot save edits.
- Web browser trying to edit an unlocked document. This is not a problem.
- Web browser trying to edit a locked document. Rep/Save conflict, if appropriate. No error messages. Note that you could program something into your form, or in a WebQueryOpen agent, to check for $Writers and give a warning to web users if a value is found in that field.
- ND6 client trying to edit a document on an R5 server. The following error message displays:
"Server does not support this version of the network protocol."
Note that your ND6 client will have the menu option to Lock/Unlock, but the server is not able to support that call.
In summary, this is a very smooth feature if the database replicates among Domino 6 servers that can easily communicate with each other, and if the users have ND6 clients. If your system is not set up this way, you should do appropriate testing to ensure that you can at least train your users as to what error messages or problems they may encounter.
Auf jeden Fall: Zurückrepliziert wird da nix. Und: Locking widerspricht den Notes-Grundprinzipien, es sei denn ... aber siehe oben.
HTH,
Bernhard
Thema: Administration Server, Document Locking und Replikation (Gelesen 2174 mal)